How to interface with C library using JNA

I have an old unix c application (.exe) which uses ActiveMQ as a message exchange to another application.

Now, I will be developing/modifying a java application using eclipse and implement JNA (Java Native Access) to use above application, which I will convert first to a library, and removing ActiveMQ implementation.

Since I am removing ActiveMQ, I dont know what technology I can replace with it to still have some message exchange from Java to C library and vice versa (in threads because the message exchanges are asynchronous)